The Nine-spotted Ladybug used to be
one of the most
commonly encountered
ladybugs throughout its
historic range (shaded area). In recent years, it has
declined to the point
which it is now
only infrequently
encountered.

ABOUT "BENEFICAL" INSECTS:

Humans have a long history of introducing non-native species
they think are beneficial.

They might introduce them to control
weeds and pests, to provide game, or for nostalgia. Humans also have
an equally long history of not fully appreciating or understanding
the consequences of these introductions.

An example is how the Seven-spotted Ladybug affected the native Nine-spotted Ladybug. The Nine-spotted Ladybug was the most common ladybug in New York state until the 1940s. Then its population rapidly dropped. This was likely caused by the introduction of the closely related Seven-spotted Ladybug. The Nine-spotted Ladybug is the official New York state insect. Yet, it has not been collected
in the state in recent decades. Over 100 species of
ladybugs have been intentionally introduced to North
America. Almost all ladybug species are predators of
aphids, so they are given the label “beneficial.” Many
native ladybug species, however, are in decline. This
is thought to be the result of these introductions.

HONEY BEE

Apis mellifera

The Honey Bee is native to Europe, the Middle East, and Africa.
It was introduced by colonists for honey production starting
in 1622. Today, it is valued as a pollinator for many agricultural
crops and for honey production.
Colonists of North America cleared, altered, and degraded
land. Native species were harvested and many non-native
species were introduced. At that time, there were many
native bees that served as pollinators of native plants. There
is little documentation of the effects these changes had on
existing native pollinators and other native species as well.
We will never really know how many native species were
affected by the Honey Bee.

Today, the Honey Bee is uniquely beneficial to humans. It is
the most important managed crop pollinator throughout most of
the world. The recent concern about reductions in Honey Bee
numbers, as a result of parasitic mites and Colony Collapse
Disorder, is a major concern that scientists are trying to unravel.

Kevin D. Arvin, Bugwood.org

Tachinid Fly

Compsilura concinnata

This fly is native to Europe and was released
in 1906 to control the Gypsy Moth. Their
maggots are parasitic. The fly deposits a
maggot directly into the host larva, killing
it within seven days. Unfortunately, the fly
has also been implicated in the decline of
native eastern species of silk moths. It is
also known to parasitize 200 alternate native
species, including beetles, bees, and moths.

Gypsy Moth

Lymantria dispar dispar

Gypsy Moth is native to Europe. In 1869,
an amateur entomologist introduced them
in Massachussets. He thought their cocoons
could be used to develop a silk resource
outside of China. This was not so, and by
1898 the Gypsy Moth had become a major
pest in the United
States. Their
larvae feed on
an estimated 300
to 500 species of
potential plant
hosts! Repeated
defoliation stresses
and can kill trees.

Female Gypsy Moths cannot
fly. It spreads mostly by
humans moving vehicles or
equipment with egg masses
laid on them to other areas.
Egg masses may contain 100 to 1,500 eggs.

Caterpillars disperse
short distances through
ballooning, riding in the wind on strands of silk.

Peter K. Ducey, SUNY Cortland

Earthworms: Friend or Foe?

Many introduced species have been around so long, people
believe they are native. Glaciers from the last ice age wiped
out earthworms in parts of North America. Earthworms are
suspected to have come to North America over the last 500 years
from Europe and Asia. They have several means of introduction
and spread. They may have been transported accidentally in soil
with plants and in ship ballast.

They can also be intentionally
introduced to assist agriculture and composting, or for bait.
Earthworms break down leaf litter, recycle soil nutrients, and
create soil burrows. Good for gardens and agriculture, these
same activities can be harmful
in native forests and fields.
Earthworms may alter forest floor
soil habitats by eating too much leaf
litter. This might change which plants
and animals can live in these areas.

Peter K. Ducey, SUNY Cortland

An Invasive Earthworm Predator: Broadhead Planarian

Bipalium adventitium

Wandering Broadhead Planarian is native to
Asia. It was probably introduced accidentally
to North America in
the early 1900s in soil
of horticultural plants.
This soil flatworm is
now found across the
northern United States.
These planarians are
aggressive predators
of earthworms,
attacking and killing
earthworms many times their own size.
Scientists are investigating whether the
flatworms eat enough earthworms to change
the sizes of earthworm populations..

Scott Bauer, USDA

Multi-spotted Asian Ladybug

Harmonia axyridis

The Multi-spotted Asian Ladybug is native to Asia. It was
first introduced to the United States in 1916. Over the
years, it has been repeatedly introduced to control aphids.
Because of its large populations, the Multi-spotted Asian
Ladybug is implicated in the decline of native ladybugs
across the United States.

The Multi-spotted Asian Ladybug
overwinters indoors and is considered a nuisance. It can
gather by the hundreds, staining walls and ceilings. In
western New York, the adults are known to nibble on
grapes, probably for the water content. It will occasionally
bite people.